How lean is too lean?

[Trumanbuckley1]

Hello, I'm curious as to what is too lean on decel. I have a 73 c20 with a 4.8 in it with a sloppy stage 2 cam, tbss intake, 3 bolt throttle body, throttle blade drilled out to a 5/32 bypass hole, stock exhaust manifolds to 2.5in dual exhaust no x/h pipe, 50lb Delphi 12613412 injectors, walbro 255 inline pump. As soon as I let off the gas and close the throttle plate it goes super lean and stays lean until I get back into it. I assume this is normal, but how lean that normal is is what I'm not sure of. Currently I'm still just trying to dial in the VE table. Any tips or pointers would be awesome, thank you in advance.

73swap after first drive.hpt
first long drive.hpl
73swap after first drive back.hpt
drive back.hpl

[kevin87turbot]

It's normal for it to be lean on decel. Most OE strategies include DFCO, Decel Fuel Cut Off.
Your DFCO is disabled, but it's ok for the AF ratio to be lean during deceleration.

[outlaw_50]

As kevin87turbot said, its normal if you lift your foot of throttle

[Trumanbuckley1]

Does everything else seem to be okay for now?

[5FDP]

No.

That VE table is a complete train wreck, I have no idea how you it got that way. The MAF dtc's need to be MIL on first error for speed density.

Use your wideband with a wideband error to correct the VE table after you fix the stuff below.

You need to put your stoich table back to the correct value for the fuel you are running. You can't put it at 13.52 if you are not running that type of fuel. The open loop EQ ratio must be 1.00 and not .96, that is screwing the VE table up also. This is not a carburetor and you can not treat it like one.

Did you put in all the injector data or just slap the table with 50lb/hr because that what size they are? You still need the min injector pulse, short pulse adder and offset vs volts data.

The PE eq ratio needs to change as well. You are asking for 13.6 AFR at wide open throttle when you need to be asking for something like 12.2 to 12.5. Change it to 1.200 for starters.

I know this is new to you but don't just slap numbers in tables because all it does it make things worse. I tired to help in your other thread but you made a new one, multiple threads just spread stuff around.

Fine the stock injector data for those injector and use this GEN 4 to GEN 3 injector spreadsheet to get the data to work.

[Trumanbuckley1]

I had been using the wideband error graph to fix the VE but it wasn't working since I didn't have the MAF fully disabled. Thank you for the reply and I will work on it

[Trumanbuckley1]

I think I fixed all the things you suggested to fix, thanks for the help. I reset the VE table until tomorrow when I try to dial them in with the error graph

73swap actually maybe a good start.hpt

[village_idiot]

Since this is a swap, does it have cats? rear o2s? egr? There's a lot of basic things to be omitted/changed if it's like most swaps and it no longer has any of these items

[Trumanbuckley1]

Does not have cats, rear or front o2s, or EGR

[village_idiot]

Why would you remove the primary o2's?

[Trumanbuckley1]

Why run them if you're using a wideband?

[village_idiot]

The wideband does not report to the PCM. In closed loop mode while normal cruising, the primary o2's will be making constant adjustments to the fuel trims to help with drivability.

If you absolutely want to, you can tune it in open loop 24/7 and monitor your wideband yourself, but at that point you nearly have a carburetor

[blindsquirrel]

A million years ago I had a leftover TPI intake, no harness or ECM. Sold it to a guy and he said he didn't need no damn stupid computer, he was going to just hook up a toggle switch on the dash for the injectors.